Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/1/2007
Publication Date: 5/1/2008
Citation: Zhang, X., Singh, R., Kolmer, J.A., Huerta-Espino, J., Jin, Y., Anderson, J. 2008. Inheritance of Leaf Rust Resistance in the CIMMYT Wheat Weebill 1. Crop Science. 47:1037-1047.
Interpretive Summary: The wheat cultivar called Weebill 1 that was developed by the international wheat breeding center, CIMMYT, is very resistant to the disease called wheat leaf rust. This study was conducted to determine what genes for leaf rust resistance are present in Weebill 1. In a genetic analysis the gene Lr14b, and a new gene that gives resistance in seeedling plants were determined to be in Weebill 1. The analysis also indicated that there were possibly three other genes in Weebill 1 that gave resistance to leaf rust in adult plants only. One of these genes was on the same chromosome as gene Lr14b. These results can be used by wheat breeders to develop wheat cultivars with improved resistance to wheat leaf rust.
Technical Abstract: The CIMMYT spring wheat Weebill 1 has near-immune levels of adult plant resistance (APR) to leaf rust caused by Puccinia triticina. To determine the genetic basis of this APR to leaf rust Weebill 1 was crossed with two susceptible parents Jupateco 73S and Thatcher. Advanced F4:5, F4:6 and F5:7 recombinant inbred lines (RIL) populations from Jupateco 73S/Weebill 1 and BC1 F2 populations from Thatcher/Weebill 1 were derived. The F5:7 RILs and BC1F2 families were tested as seedlings with five races of P. triticina. The F1 and F4:5, F4:6, and F5:7 RILs of Jupateco 73S/Weebill 1 were evaluated in field plots in Mexico and St. Paul. The Jupateco 73S/Weebill 1 RILs and Thatcher*2/Weebill 1 F2 families segregated for Lr14b, an unknown seedling leaf rust resistance gene derived from Weebill 1 in both crosses, and Lr17a derived from Jupateco 73S in the RIL population. The seedling genes did not condition effective resistance in the field plots with races used in the field trials. The segregation ratio in the RILs and F2 families indicated the presence of three to four APR genes in Weebill 1. One of the APR genes was linked to the seedling gene Lr14b on chromosome 7BL and reduced leaf rust by 47% in St. Paul and 31% in Mexico. Lr17a was mapped to the distal end of chromosome 2AS and was linked to microsatellite maker Xgwm636 at a distance of 4.0 cM.